This invention relates to fence tensioners especially designed for use with flexible polymer fence slats.
Fences are the most commonly employed means for confining that which would otherwise escape and excluding that which would otherwise intrude. Fences may vary greatly in both structure and materials of composition. Common fence structures include wire fences, such as barbed wire and chain link, and wood fences such as, picket fences and split rail fences. Common fence materials include metal, wood and stone. Fence structure and composition are selected on the basis of initial and upkeep costs, durability, strength, aesthetic characteristics, and safety desired or required.
One very common form of fencing is barbed wire. The relatively low cost of purchasing, installing, and maintaining barbed wire fencing has made it the preeminent fencing material for enclosing livestock areas. Barbed wire suffers from the disadvantage, however, that its sharp barbs may cut or gouge the hide of valuable livestock. Furthermore, barbed wire has a very thin cross-section so that it is not easy to see; and an animal is correspondingly more apt to contact a barbed wire fence than it would be to contact a more visible barrier. Other types of wire fencing known in this art, such as web wire fencing, and cyclone wire fencing, suffer from similar limitations. These wire fences also tend to have poor aesthetic qualities and they tend to rust or corrode after a few years of service. Fences made entirely of wood, on the other hand, are typically safer and more pleasing to the eye, but are expensive to install and maintain.
Over the past several years, composite metal and plastic fence systems have become increasingly accepted for the confinement of livestock, thoroughbred horses and the like. Typically, the fence slats are comprised of at least two wires or other high strength fibers encased in a polymer such as vinyl or other suitable plastic web. Depending on the width of the fence slat, two wires may extend along the opposite edges of the slat or, for wider slats, a third wire may be added intermediate the edge wires. Examples of such fencing construction can be found in U.S. Pat. Nos. 4,465,263 and 4,706,942.
To maximize the effectiveness of the flexible fence slats, tensioning devices must be utilized to insure that the individual slats do not sag between posts. Fence tensioners have long been used to tighten individual strands in wire fence systems. Examples may be found in U.S. Pat. Nos. 393,504; 420,819; 473,899; 516,040; 596,987; 658,671. A fence tensioner for polymer fence slats is disclosed in the more recently issued U.S. Pat. No. 6,152,429.